Chevy Corvette C5 Simple Bolt-On Upgrades - Nip Tuck

Comp Cams was just aching for us to test out their new Ultra-Gold 1.82 ratio rocker arms (p/n 19025-16). These things look like jewelry, it's a shame they'll be hidden underneath the stock aluminum valve covers. With the increase in valve lift, we expected quite a few extra horsepower. And with Comp's rep on the line we expected durability and a great fit from the aluminum, stud-mounted roller rockers. List price is $482.83 for the whole set.

On some model years, it will become necessary to upgrade the valvesprings (unless you like the sound of valve float). We opted for Comp's 918 beehives for their weight, durability, and fit. We paired p/n 26918-16 with titanium retainers (p/n 772-16), and machined steel valve locks (p/n 623-16). The whole lot will run you $480.02.

The coil packs are removed with a 10mm socket and the valve covers use an 8mm socket.

...removed with an 8mm socket.

With the air compressor hooked up to the spark plug hole, the stock springs are compressed and removed. The Comp 918s, titanium retainers, and steel locks then immediately replace them.

The rockers are stud mounted, using a 6mm Allen head,...

...which needs to be torqued to 28 ft-lbs (factory spec).

After starting with a street tune (using EFI Live to tweak the factory PCM), ECS co-owner Doug Ring strapped the C5 back down to the Dynapack dyno. The roller rockers seemed to cause some false knock right out of the gate, which was easily amended by desensitizing the knock sensor. Once the computer stopped pulling timing it hit 333 hp, and Doug was able to start putting a few more degrees of timing to it.

With the final tune, ECS had taken the anemic stock C5 all the way up to 343 hp and 353.6 lb-ft of torque. That's a total gain of 68.5 hp and 47 lb-ft with no sacrifice to reliability, gas mileage, or overall satisfaction. And best of all, that's well within striking distance of a stock C5 ZO6. Now imagine what we could do with a good set of headers!